Dynamics study of constant diastolic interval and constant TR control for cardiac alternans based on a two-dimensional cellular automata model

As a precursor for cardiac arrhythmias such as atrial and ventricular fibrillations, which could cause sudden cardiac death, cardiac alternans is essentially an unstable heart rhythm with alternating long and short action potential durations (APD) of cardiac myocytes that usually occurs under fast pacing conditions. In this paper, the constant TR control method based on a global pseudo-electrocardiogram (ECG) is studied and compared with the local constant diastolic interval (DI) control method using a 2-dimensional (2-D) cellular automata model (CAM), aiming at preventing or eliminating cardiac alternans before arrhythmias. The results show that both the constant TR and constant DI control methods are effective in stabling the alternans to a smaller basic cycle length (BCL). Also, the efficacy of the two control approaches depends on the “decrease step” Δ in the downsweep protocol, and a smaller Δ could significantly improve their performance. In addition, constant TR control is generally superior to constant DI control in alternans prevention when a relatively large Δ is adopted.